There are a number of situations in which contamination such as a change in acidity or alkalinity of a fluid circulating within a closed system can damage components within the closed system. In refrigeration systems, for example, lubricating oil is entrained in refrigerant which is circulated by a compressor through a closed set of components. The compressor must be continually provided with lubricant including the entrained lubricating oil. Refrigerants break down over time, however, leading to formation of strong acids or bases which attack the compressor and other critical components of the refrigeration system.
Presently, lubricating oil is monitored by removing samples from the crankcase of the refrigeration compressor. The acidity of the sample is tested remote from the refrigeration system by wet chemical titration or by measurement of resistivity during titration to indicate when neutralization of the lubricant occurs. During sampling, however, the compressor is typically shut down to avoid the hazards of burns, injury from rotating fan blades, and electric shocks associated with working on an operating machine. Further, the oil darkens and becomes increasingly opaque as it becomes contaminated, making it increasingly difficult to detect the end point of titration.
One apparatus for withdrawing oil from a refrigeration system connects across the compressor or condenser and withdraws refrigerant into a chamber. When a quantity of oil has accumulated, the apparatus is disconnected and the oil drained from the chamber. This procedure may well remove enough oil from the system to cause mechanical damage to bearings, pistons and cylinder walls due to inadequate lubrication. Moreover, the oil is not continuously monitored and serious chemical damage may result to refrigeration system components before the sample is taken. Further, any contamination which arises after sampling will not be detected until the next manual sampling procedure.